Bicycle MechanicsBroken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Guys, I'm struggling a bit getting my front mech to index properly. I upgraded from LX to XTR. My XTR (downpull) fits on the bb and I routed a new cable into it. I'm using an SRAM XO shifter. With the front mech fully relaxed (no tension) I routed the cable onto it, gave it a firm-ish pull to take up the slack and tightened it down. I can rotate the shifter 1-2-3-2-1 and it pulls and releases snappily enough. It'll index reasonably ok on the middle and outer chainring, but it won't drop down to 1 at all, though it tries to. I started with full-in and then out-one turn on the barrel adjuster. When I had overhauled my LX I was able to get the indexing more or less spot on. This is my first excursion into XTR territory. I reckon it's just a simple tweak with the hi/lo screws but I'm not sure which ones do which on XTR as I read somewhere that the top or botton swing whichever one it uses reverses the action of the hi/lo screws.

Can anyone advise me and steer me through the last process? Maybe XTR is intrinsically 'superior' to LX on account of the machining and accuracy where LX is perhaps more 'forgiving' in the settings?

Bikes: Catrike 559 I own some others but they don't get ridden very much.

Posts: 26,914

Mentioned: 3 Post(s)

Tagged: 0 Thread(s)

Quoted: 213 Post(s)

Try this:

1. Disconnect your shift cable.
2. With the shift cable disconnected, it will be easy to see what is happening when you mess with the limit adjustment screws. Fiddle with them until you get the derailleur to move inward a little. Don't move it in too far.
3. I use my needle nose pliers to pull the shift cable taut before I attach it and seldom have to make a barrel adjustment afterward.

It was a combination of cable tension and screw settings. The XTR mech sheet mentions the screws are reversed but that's all. The action is the same you just have to think about the reversal as instinctively you reach for lo and adjust hi instead! I also had too much cable tension so the mech could not retract fully when dropping into granny gear. I loosened the cable, made small tweaks on the barrel adjuster until it just about started to shift, and then used the screws to make the final tweak.

I went for a short post-fix ride and I have to admit, it shifts absolutely sweetly. I can say I notice a difference between LX and XTR. The mech is much snappier and positive in action. I don't mind the price I paid for it. I also upgraded the bb and that slight clunk I used to feel and classic bb creak on hard pedalling is now gone and the new bb is silky smooth. The job I think, is a good 'un.

Next mission is to strip down the rear cassette and clean it thoroughly. Then I'll bleed the brakes and should see me through until I think of something else to do!